Dr. John J. TYSON is University Distinguished Professor of Biological Sciences and a fellow of the Virginia Bioinformatics Institute at Virginia Tech. He received a PhD in chemical physics from the University of Chicago, and did postdoctoral research in biophysical chemistry and cell biology, before moving to Virginia. Dr. Tyson is an expert in modeling molecular regulatory systems within cells, especially the networks that control cell growth, reproduction and death. His detailed models of cell cycle regulation in yeast are often cited as paradigms of a systems approach to understanding the molecular basis of cell physiology.